1. Field of Use
The present invention relates generally to devices and methods used to locate misplaced or lost articles and, more particularly, to an electronic sound detecting and indicating circuit which produces an auditory response upon detection of a sequence of sounds having frequencies, time spacing and amplitude levels falling within predetermined ranges.
2. Related Art
Everyone, at one time or another, has temporarily misplaced his or her keys, eyeglasses, wallet, or the like. Who among us has not experienced the frustration of being unable to find his keys, which he just had a moment or two ago? Who among us has not spent valuable time rummaging through clothes, desks, dressers, drawers, purses, and the like, in a frustrating attempt to locate a misplaced object? Articles such as eye-glasses, keys and the like, are misplaced with great frequency, and consequent inconvenience and frustration to the individual. It would be highly desirable, therefore, if an inexpensive, reliable, and practical device could be provided to assist all of us who, at one time or another, have experienced this.
I am aware of one previous United States patent which teaches a device for locating commonly misplaced objects. U.S. Pat. No. 4,101,873 to Anderson et al. teaches a receiver that is attached to a commonly misplaced object. The user determines the location of the misplaced object by generating a predetermined code transmission using a transmitter. The receiver detects the predetermined code signal and provides an audible output if a proper code sequence is detected. International application No. PCT/GB81/00243 similarly discloses a two-device system comprising a short range signal transmitter or "searcher" and a receiver or "locator". Signalling between the two units may be either by ultrasonic or electromagnetic waves.
There are difficulties in the use of a two-device system (transmitter and receiver) in that, in order to find the object, the transmitter must be available and, hence, it must be located or fetched first. What does one do if one cannot find one's transmitter? A two-device system is also likely to be more expensive than a one-device system.
In addition, the problems associated with radio receivers of the type disclosed by the U.S. Patent and PCT application noted above are numerous. They require complex filters, R. F. oscillators, mixers and tuning networks. Many such items cannot be integrated (such as the tuning coils). Hence, integration of the elements into a cheaper and more easily assembled unit cannot be done. This renders such systems fairly expensive and out of the range of the ordinary consumer.
The present invention overcomes the above-noted disadvantages by providing a single electronic unit which may be easily fabricated on a microchip thereby reducing the cost of mass production, increasing reliability, and eliminating the vagaries associated with a transmitter-receiver system. As will be explained more fully below, the present invention comprises a single self-contained unit which does not require a separate transmitter. The present invention is responsive to human-generated sounds so that a person may locate his missing keys, for example, by simply clapping his hands.